Step-by-step installation of a pressure tank to a home water treatment system
Step-by-step installation of a pressure tank to a home water pump system
The pressure tank is the heart of every home water pump system. Without it, the pump would switch on every time a tap is opened, which would lead to rapid wear and unpleasant water flow interruptions. A properly installed and adjusted pressure tank prolongs the life of the pump, stabilizes the pressure in the installation, and ensures convenient water use throughout the house. Despite this, I often encounter customers who underestimate the installation – they either forget to fill the tank with air before installation, close the water supply before releasing air from the pipes, or choose an unsuitable location and after a year they deal with condensation, rust, and cracks in the walls. This article will guide you through the entire process – from the first unboxing of the tank to the final pressure test – with specific values, dimensions, and examples from real customer cases.
If you are still considering which tank to buy, I recommend reading the articles How to choose a pressure tank for a home water pump and What pressure tank capacity do I need for my house in this Knowledge Center first. Here I assume that you have already selected the correct model and capacity and are ready for the actual installation.
What you will need: tools, seals and materials
Before starting any work, prepare everything at once. This will save you unnecessary running around and reduce the risk of errors caused by haste. From experience, I know that missing small items – one seal, one coupling – are the reasons why installation that should take two hours stretches into a whole day.
- Pipe wrenches (adjustable, preferably two – for fixing and tightening)
- Teflon tape or hemp fiber with sealant (e.g. Fermit, Loctite 55)
- Pressure gauge (if not part of the pressure group)
- Tire pressure gauge or low-pressure pump (for checking the air pre-pressure)
- Three-way ball valve or service valve
- Check valve (if not part of the pump)
- Pressure group (pressure switch + pressure gauge + safety valve in one block, or each separately)
- Stainless steel or brass couplings and reducers according to the specific installation
- Appropriate connecting material – threaded or crimped fittings for PE/Cu/PP pipe
- Anti-vibration pads under the tank (rubber, neoprene)
- Drain pan or drain hose (in case the safety valve discharges)
Electrical installation tools (screwdriver, pliers, insulating tape, cable lugs) should also be prepared if you are connecting the pump and pressure switch yourself. For pumps over 1 kW, I recommend entrusting the electrical connection to an electrician.
Choosing the installation location: what many underestimate
The pressure tank must be placed on a solid, level and dry base. Typical locations are a technical room, basement, boiler room or garage. It is important that the room temperature never drops below 0 °C – the tank with water must not freeze. Experience shows that customers in non-insulated garages or sheds often neglect this and are awakened in January by bursting pipes.
Leave enough space around the tank for maintenance – at least 50–60 cm on each side where you will be working. For large vertical tanks such as Galvanized pressure tank HVP 300L with a height of about 140 cm, also check the clear height of the room and the width of the door (bringing the tank into the basement can be an adventure in itself). Vertical tanks stand on legs or a saddle base – check whether the floor is level, and if necessary, use leveling elements.
Horizontal tanks of smaller capacity, for example Horizontal pressure tank AQUA OLA 24l, are mounted directly next to the pump, which is ideal for compact pumping systems in smaller houses. They are easier to handle and do not require as much vertical space.
Preparing the tank before installation: air pre-pressure
This is a step that people most often skip and then wonder why the tank is not working properly. Before connecting it to the system, you must check and set the air pre-pressure in the tank. Tanks with a bladder (membrane) and some galvanized tanks with an air cushion are filled with air at a certain pressure at the factory – usually 1.5 bar or less – but this value may not match your installation.
Basic rule: the air pre-charge must be set to a value 0.2–0.3 bar lower than the pump's pressure switch (p-on) setting. For example, if the pump turns on at 1.8 bar, set the air pre-charge in the empty tank to 1.5–1.6 bar.
You check and adjust the pre-charge through an air valve (a Schrader valve, the same type used on tires). The tank must be completely empty of water at that moment – if it is already connected, close the water supply and drain the tank. Then measure the air pressure with a pressure gauge. If it is low, inflate it using a standard hand pump or compressor. If it is too high, release air through the valve. An accuracy of ±0.1 bar is sufficient.
In galvanized tanks without a bladder – for example, Galvanized pressure tank HVP 200L – there is no membrane or bladder, and air and water are in direct contact. This affects proper installation and long-term operation (air gradually dissolves in water), as explained in the article Pressure tank with bladder or without – what is the difference. For these tanks, it is important to maintain the correct water level relative to the air cushion – usually water occupies 2/3 of the volume, and air 1/3.
Step 1: Mechanical installation – securing and positioning the tank
Vertical tanks (most models above 50 liters) are placed directly on the ground on their own feet. Check the level with a spirit level. If the feet are not adjustable, use rubber pads underneath. Never place just pieces of wood under the tank – over time, they deform, the tank tilts, and this puts stress on the connection.
With Stainless steel pressure tank CH 300L, we are talking about a tank weighing approximately 45–50 kg empty, and 345 kg when fully filled – the floor must be sufficiently load-bearing. In an older basement with a sandy floor, I recommend a concrete slab at least 10 cm thick.
Smaller horizontal tanks can also be mounted on the wall using brackets, but for weights over 15 kg (when full) and dynamic load from pressure pulsations, it is better to choose a standing solution on the floor. AQUA OLA 24l horizontal weighs about 26 kg when full, which is still manageable for wall mounting, but use certified anchors in the wall with a load capacity at least three times the weight.
Step 2: Hydraulic connection – the order of components is important
Most amateur plumbers make a mistake here. The correct order is: pump → check valve → pressure group (pressure switch, pressure gauge, safety valve) → pressure tank → distribution to the house. Not the other way around.
The pressure tank must be connected after the pressure switch (or in parallel if the pressure group is implemented as a T-branch), not before it. The pressure switch must "feel" the pressure in the system, including the pressure accumulated in the tank – otherwise, the pump will not switch on correctly.
Step-by-step connection procedure
1. Threaded connection on the tank inlet: Most tanks have one water inlet with a G 1" or G 1¼" thread (depending on the size). Check the thread, wrap it with 3–4 layers of Teflon tape in the direction of the thread, or use hemp fiber with sealant. Tighten with a wrench – firmly, but without excessive force that could crack the tank body.
2. Installation of a service valve: Always insert a ball valve or service valve between the tank and the rest of the system. This allows you to disconnect the tank without draining the entire system – for example, when replacing the membrane, adding air, or replacing the tank. This will come in handy at some point.
3. T-branch and pressure group: On the main pipe (between the pump and the distribution), install a T-branch, from which a branch leads to the pressure tank. On this branch (or directly on the T-branch, depending on the configuration), connect the pressure switch and pressure gauge. The safety valve should be connected so that its outlet points to a drain or siphon tray – not freely into the space.
4. Check valve: If the pump does not have a built-in check valve, install one on the pump's discharge port (immediately after the pump). The check valve prevents water from flowing back from the tank into the well when the pump is off – without it, the system would "drain" every time the pump turned off, and the pump would switch on much more frequently.
Step 3: Pressure Switch Adjustment
The pressure switch is an electromechanical device that closes and opens the pump circuit according to the pressure in the system. It is supplied by default with a setting of p-on (pressure on) = 1.5 bar and p-off (pressure off) = 3.0 bar, which corresponds to a differential Δp = 1.5 bar. These values are suitable for most household water systems, but it is good to check and possibly adjust them.
The adjustment is done using two screws under the switch cover:
- Main screw (larger spring, labeled "P" or "Main"): Increases or decreases both pressures simultaneously (shifts the entire range).
- Differential screw (smaller spring, labeled "ΔP" or "Diff"): Changes only the difference between p-off and p-on.
For a typical family home and a water source at a depth of 15–25 m, a suitable setting is p-on = 1.8–2.0 bar, p-off = 3.5–4.0 bar. A larger differential = longer intervals between pump switching = longer lifespan. Remember: the air pre-pressure in the tank must always be 0.2 bar lower than p-on!
If you are unsure about the settings, read the article What pressure to set in the pressure tank and how to check it in this Knowledge Center – you will find detailed tables with recommended values according to the well depth and house height.
Step 4: Electrical Connection of the Pressure Switch and Pump
The pressure switch is a switching element in the pump's power circuit. It contains switching contacts (usually NO – normally open), through which the pump's supply voltage passes. It is connected in series with the pump on the phase conductor.
For a pump with a three-phase motor (400V/3f), the connection is more complex – the pressure switch switches the contactor coil, not the motor directly. In such a case, I really recommend an electrician. For typical household water systems with a single-phase pump (230V, up to approx. 1.5 kW), the connection is simple:
- Phase conductor from the grid → pressure switch contacts → pump phase
- Neutral conductor from the grid → directly to the pump
- Protective conductor (PE) → frames of both devices
The circuit must be protected by a circuit breaker with a current rating corresponding to the pump's power (usually B10 or B16 for 1–2 kW motors). Never connect the pump without a circuit breaker!
Step 5: First Start and System Air Removal
This is the moment of truth. It should look like this:
Before starting the pump: Open the service valve at the tank. Check that all connections are tightened. Leave one tap in the house open – it will serve as an air vent. For a pump drawing water from a greater depth, fill it with water (pour into the suction pipe via a removable thread or through the primary valve).
Starting: Turn on the pump. For the first 10–30 seconds, it may make a loud suction sound and pulse – this is normal, as it is pushing air out of the suction pipe. When p-off is reached, the pump will turn off. Check the pressure gauge.
Air removal: Let water flow from the open tap until all air is gone. Then close the tap and monitor the pressure gauge – the pressure should slowly drop (water is filling the tank) and stabilize at a certain level. If the pressure drops sharply to p-on and the pump immediately switches on again – there may be a problem with the air pre-pressure or the membrane is damaged.
Sealing check: Go through all connections and visually check for any dripping. Dry the wet spot and possibly tighten or replace the sealing. Never tighten connections under pressure while the pump is running.
Step 6: Final Pressure Test and Adjustment
After a successful first start, let the system run for a while – ideally the whole day in normal operation – and then check several parameters:
- Pump switching frequency: During normal use (hand washing, toilet flushing), the pump should switch on at most 1–2 times per minute. If it switches on with every tap opening, the tank pressure or air pre-pressure is incorrect, or the tank volume is too small.
- Pressure at p-off and p-on: Check via the pressure gauge and compare with your switch settings.
- Visual sealing check: After 24 hours of operation, check all connections again. Some sealing materials "settle" after loading and may drip slightly.
- Room temperature: Check that condensation on the tank is not excessive – the tank should be dry on the surface.
Common Mistakes and How to Avoid Them
Over the years I have encountered household water system installations, I keep seeing the same mistakes. Here are the most common ones:
Mistake No. 1 – Missing air pre-pressure. The customer installed the tank directly from the box without measuring and setting the air pre-pressure. Result: the pump switches on every 3 seconds, the pump's memory wears out in a fraction of its lifespan. Solution: always measure and set the pre-pressure before connecting.
Mistake No. 2 – Missing check valve. Without a check valve, water returns to the source every time the pump is turned off, the pressure in the system drops to zero, and the pump immediately starts again. A system without a check valve behaves as if the pressure tank wasn't there at all.
Error No. 3 – Pressure tank connected before the pressure switch. The switch "does not see" the actual system pressure, which leads to chaotic switching. Always: T-junction (to the tank and to the switch) must be in the same place – after the pump and check valve, before the house distribution.
Error No. 4 – Inappropriate sealing or overfilling with Teflon. Too thick a layer of Teflon can cause the tank or switch thread body to crack when tightened. Correct thickness: 2–4 layers, evenly wound.
Error No. 5 – Safety valve without a drain. If the safety valve (usually set to 5–6 bar) opens without a drain, it will flood the entire technical room. Always connect a drain hose or a siphon basin.
Error No. 6 – Installation in an unheated space. Water in the tank and pipes will freeze. At -10°C, every tank and every pipe will crack without exception. If it is not possible to choose a heated space, the pipes must be well insulated and in extreme cases, electric de-icing heating should be added.
Specifications for different types of tanks
Galvanized tanks without a bladder
These tanks (e.g. HVP 200L or HVP 300L) have air and water in direct contact. During installation, it is important to ensure that the air chamber is correctly set. These tanks are delivered without air or with minimal pre-pressure – before connecting, fill them with air to the required level. In vertical position, water enters from the bottom and air remains on top – always install them vertically, otherwise air could get into the supply.
Stainless steel tanks with a membrane
Stainless steel tanks such as CH 90L or CH 300L usually have a built-in membrane or bladder that separates air from water. Pre-pressure is set the same way via a Schrader valve, but the membrane means that air does not dissolve into the water – these tanks maintain pre-pressure more stably in the long term. During installation, be careful not to place the tank on its side during handling – the membrane could be damaged when filling with water in a horizontal position.
Horizontal tanks of smaller capacity
Horizontal tanks up to 50L are typically installed directly into a compact assembly with a pump. Their advantage is lower height – they fit under a sink or into a low cabinet. The disadvantage is a smaller usable volume (recommended volume for family use is at least 50–80L, for larger houses 100–300L). Always secure horizontal tanks so that they cannot tip over or shift – anti-vibration pads are mandatory.
Maintenance after installation: what and when to check
Installation itself is only the beginning. A properly functioning pressure tank requires regular maintenance, which is often underestimated. A detailed article Maintenance and service of pressure tanks – what and when to check covers this topic in depth; here is a summary of the basic intervals:
- Every 3 months: Visual inspection of the seal, check the pressure gauge, listen for abnormal pump sounds.
- Every 6 months: Measuring air pre-pressure (with the tank drained).
- Once a year: Comprehensive inspection – pre-pressure, check the check valve function (try stopping the pump and observe whether the pressure holds over time), check the membrane, lubricate the switch's moving parts.
- Every 5–7 years: Replacement of the membrane or bladder (for membrane tanks), or a full system review.
If you notice any of these symptoms, do not wait for the next inspection: the pump switches more than 5–6 times per minute, the pressure in the system "pulses" visibly in the tap water, water comes out of the air valve when opened (a burst membrane), the safety valve discharges water on its own. These faults and their solutions can be found in the article Common pressure tank faults and how to fix them.
Most frequently asked questions (FAQ)
Do I have to drain the entire system to set the air pre-pressure?
Yes, when setting the air pre-pressure, the tank must be empty of water, otherwise we are not measuring the air pre-pressure, but the total system pressure. Close the service valve at the tank, open the nearest tap in the house and let the water run until the pressure drops to zero on the pressure gauge. Only then measure and set the air pressure via the valve. After setting, close the tap, open the service valve and restart the system.
What happens if I set the air pre-pressure higher than p-on?
If the air pre-pressure is higher or equal to the pump's turn-on pressure (p-on), water will practically not enter the tank – the tank will not accumulate any energy and the pump will switch on with every small draw. The system will function as if there was no pressure tank at all. Always apply: air pre-pressure = p-on minus 0.2 bar.
Can I connect the tank with plastic (PP or PE) piping or must it be metal?
PP or PE piping is fully suitable for home water systems if it has the corresponding pressure rating (PN 10 or PN 16). For pressures up to 4 bar (which is typical for home water systems), PN 10 is sufficient. Make connections either with pressure fittings (clamping or crimped) or with brass threaded adapters. Do not use ordinary garden hoses – they are not designed for continuous pressure loading.
What size pressure tank is sufficient for a family house with 4 people?
For a 4-person family with a well and a pump at a depth of 20–30 m, a tank with a volume of 80–150 liters is suitable. A smaller volume (e.g. 24–50L) may be enough to suppress pulsations, but the pump will switch too often. A larger volume (200–300L) is ideal if you have garden irrigation, a pool or high consumption. A detailed calculation can be found in the article What pressure tank volume do I need for my house.
I heard that a pressure tank requires a pressure equipment inspection. Is it mandatory?
It depends on the tank's volume and maximum operating pressure. According to Slovak regulations (Decree of the Ministry of Transport, Construction and Regional Development of the SR No. 508/2009 Coll. on the safety of technical equipment), some pressure tanks are classified as designated technical equipment and require an official inspection. For home water systems with tanks up to 1000 liters and pressure up to 6 bar for non-industrial use, the rules are less strict – however, I still recommend regular self-checks and calling a professional technician once every 5 years to assess the condition.
The pump is working normally, but the water from the tap "bounces" and pulses. What is the cause?
Pulsating water is a classic sign of a burst or cracked membrane, or a zero or very low air pre-pressure. Drain the tank, check the air – if water comes out of the air valve instead of air, the membrane is definitely cracked and needs to be replaced. If the pre-pressure is just low, pump air to the correct level. The article Common pressure tank faults and how to fix them also describes other causes of pulsation.
Conclusion: correct installation pays off
Installing a pressure tank to a home water system is not rocket science, but it requires precision, patience and a proper understanding of what each component does and in what order they belong in the system. The biggest investment is in the correct setting of the pre-pressure and a functional hydraulic configuration – these are things that cannot be fixed just by tightening a bolt, and mistakes in them will cost you in the long run in terms of pump lifespan and comfort of daily water use.
If you choose a tank that meets your needs, install it correctly and regularly check it, it can easily serve you for 15–20 years without major problems. Stainless steel models such as CH 90L or CH 300L can last even longer. It mainly depends on the quality of the water source, correct pressure settings and minimal regular maintenance.
If you want to compare which type of tank is more suitable for you – with a bladder, without a bladder, stainless steel or galvanized – read the articles Pressurized tank with a bladder or without a bladder – what is the difference and Galvanized vs. stainless steel pressure tank – which is better. You can find the full range of tanks clearly listed on the Pressure Tanks category page.
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